The present invention provides compositions and methods for modulating the expression of PPP3R1. In particular, this invention relates to compounds, particularly oligonucleotides, specifically hybridizable with nucleic acids encoding PPP3R1. Such compounds have been shown to modulate the expression of PPP3R1.
A wide variety of cellular processes are linked by cascades of phosphorylation and dephosphorylation of proteins. These reactions are catalyzed by enzymes which encompass a large group of kinases and phosphatases that modify serine and/or threonine on other enzymes, receptors, transcription factors and binding proteins. The calcium- and calmodulin-dependent phosphatases represent a subset of enzymes within the larger family of serine/threonine protein phosphatases.
Calcineurin (also known as protein phosphatase 3 and formerly known as protein phosphatase 2B) is a calcium calmodulin-dependent protein phosphatase that has an important role in the control of intracellular calcium signaling. It is composed of a catalytic subunit that has high homology with other protein phosphatases, and a regulatory subunit which belongs to the EF-hand calcium-binding protein family (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275). Calcineurin mediates activation of T-cells and is involved in signaling pathways such as hippocampal long term depression, migration of neutrophils and growth cones (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275). In addition, it has been recently discovered that calcineurin integrates calcium-mediated cellular regulation of the redox potential of cells, indicating a role for calcineurin in controlling the de-energization of neuronal mitochondria (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275).
The two subunits of calcineurin are tightly bound and can only be dissociated under denaturing conditions. The catalytic subunit alone has only a very low activity and the presence of the regulatory calcium-binding B subunit is essential for the high specific phosphatase activity (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275).
The regulatory subunit gene of calcineurin is known as PPP3R1 (also known as protein phosphatase 3 (formerly 2B), regulatory subunit B (19 kD), alpha isoform; and calcineurin B, type I). PPP3R1 was cloned and mapped to chromosome 2p16-p15 and was found to be expressed in all tissues except testis. The possibility has been indicated that alternative splicing of the PPP3R1 gene may generate additional products (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275; Wang et al., Cytogenet. Cell Genet., 1996, 72, 236-241).
Calcineurin is inhibited by the immunosuppressant-immunophilin complexes FK506-FKBP and cyclosporin-cyclophilin, indicating that calcineurin plays a key role in immune function (Guerini, Biochem. Biophys. Res. Commun., 1997, 235, 271-275).
Small molecule inhibitors of protein phosphatases are well known in the art. For example, disclosed and claimed in U.S. Pat. No. 5,925,660 are methods for inhibiting protein phosphatases with small molecule inhibitors (Lazo et al., 1999).
Disclosed and claimed in PCT publication WO 00/09667 is a method of transforming a slow muscle fiber to a fast muscle fiber comprising inhibiting calcineurin activity in said slow fiber by providing an expression construct encoding a calcineurin gene positioned antisense to a promoter functional in slow muscle fiber and contacting said expression construct with said slow muscle fiber in an amount effective to decrease the calcineurin activity in said fiber (Williams and Olson, 2000).
An 18-mer phosphorothioate antisense oligonucleotide targeting the initiation codon of the rat PPP3R1 gene has been employed in an investigation of the effects of calcineurin activity on the phosphorylation state of tau protein because aberrant tau phosphorylation has been implicated in the biogenesis of the paired helical filaments observed in Alzheimer""s disease (Garver et al., Mol. Pharmacol., 1999, 55, 632-641).
The selective inhibition of PPP3R1 may prove a useful therapeutic strategy with which to treat autoimmune disorders and neurological disorders such as Alzheimer""s disease.
Currently, there are no known therapeutic agents that specifically and effectively inhibit the synthesis of PPP3R1. Consequently, there remains a long felt need for additional agents capable of effectively inhibiting PPP3R1 function.
Antisense technology is emerging as an effective means for reducing the expression of specific gene products and may therefore prove to be uniquely useful in a number of therapeutic, diagnostic, and research applications for the modulation of PPP3R1 expression.
The present invention provides compositions and methods for modulating PPP3R1 expression.
The present invention is directed to compounds, particularly antisense oligonucleotides, which are targeted to a nucleic acid encoding PPP3R1, and which modulate the expression of PPP3R1. Pharmaceutical and other compositions comprising the compounds of the invention are also provided. Further provided are methods of modulating the expression of PPP3R1 in cells or tissues comprising contacting said cells or tissues with one or more of the antisense compounds or compositions of the invention. Further provided are methods of treating an animal, particularly a human, suspected of having or being prone to a disease or condition associated with expression of PPP3R1 by administering a therapeutically or prophylactically effective amount of one or more of the antisense compounds or compositions of the invention.